Display substrate, method of manufacturing the same and display panel having the same

ABSTRACT

A display substrate includes a base substrate, a micro shutter, a first driving electrode, a second driving electrode, and a plurality of anchors. The micro shutter includes a flat portion having at least one opening, a main concave portion adjacent to the opening and extending in from the flat portion to a first depth, and at least one sub-concave portion extending in from a bottom surface of the main concave portion to second depth. The first driving electrode is connected to a first side of the micro shutter. The second driving electrode is connected to a second side of the micro shutter. The second side is positioned opposite to the first side. The anchors fix the first and second driving electrodes on the base substrate.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. §119 to Korean PatentApplication No. 2011-47401, filed on May 19, 2011, in the KoreanIntellectual Property Office (KIPO), the contents of which are hereinincorporated by reference in their entireties.

BACKGROUND OF THE INVENTION

1. Technical Field

Example embodiments of the present invention relate to a displaysubstrate, a method of manufacturing the display substrate and a displaypanel having the display substrate. More particularly, exampleembodiments of the present invention relate to a display substratehaving a digital micro shutter (DMS), a method of manufacturing thedisplay substrate and a display panel having the display substrate.

2. Discussion of the Related Art

Generally, a display apparatus displays an image or data inputted by aninput device. For example, a cathode ray tube, a liquid crystal display(LCD), a plasma display panel (PDP) and a field emission display havebeen used for the display apparatus.

Studies on applying a different mode for a display apparatus have beenperformed. An organic light emitting display (OLED) a successor to theLCD and the PDP, is a next generation display apparatus, which has begunto be commercialized. In addition, a display apparatus using a microelectro-mechanical system (MEMS), which has relatively high efficiencyfor light utilization and relatively fast switching, has been developed.

The display apparatus using the MEMS includes a first substrate on whicha light blocking layer having at least one opening is formed, a digitalmicro shutter (DMS) having at least one opening, and a second substratehaving a circuit which controls opening and closing of the DMS. The DMSmoves horizontally by an electrostatic force when an electric signal isapplied from the circuit. For example, when an electric signal isapplied to the DMS from the circuit, the DMS moves horizontally by theelectrostatic force, so that the opening of the DMS is aligned with theopening of the light blocking layer and thus light passes through theopenings. When the electric signal is not applied to the DMS, the DMSmoves horizontally by an elastic force, such as a spring force, so thatthe opening of the DMS is not aligned with the opening of the lightblocking layer and thus the light is blocked.

The DMS is spaced apart from a backplane on which the circuit is formedin a vertical direction, so that the DMS is able to move horizontallywithout interference.

However, a static friction occurs due to a molecular force of moleculeson a contact surface between the DMS and the backplane. As a result, thesecond substrate may be damaged and a yield of manufacturing the displayapparatus may be decreased.

SUMMARY OF THE INVENTION

Example embodiments of the present invention provide a display substratecapable of deceasing damage due to static friction, a method ofmanufacturing the display substrate, and a display panel having thedisplay substrate.

According to an example embodiment of the present invention, a displaysubstrate includes a base substrate, a micro shutter, a first drivingelectrode, a second driving electrode, and a plurality of anchors. Themicro shutter includes a flat portion having at least one opening, amain concave portion adjacent to the opening and extending in from theflat portion to a first depth, and at least one sub-concave portionextending in from a bottom surface of the main concave portion to asecond depth. The first driving electrode is connected to a first sideof the micro shutter. The second driving electrode is connected to asecond side of the micro shutter. The second side is positioned oppositeto the first side. The anchors fix the first and second drivingelectrodes on the base substrate.

In an example embodiment, the display substrate may further include afirst reference electrode and a second reference electrode. The firstreference electrode may be spaced apart from the first drivingelectrode, and fixed on the base substrate by at least one of theanchors. The second reference electrode may be spaced apart from thesecond driving electrode, and fixed on the base substrate by at leastone of the anchors.

In an example embodiment, the micro shutter may include a plurality ofsub-concave portions. Depths of the sub-concave portions extending infrom the bottom surface of the main concave portion may be differentfrom each other.

In an example embodiment, the sub-concave portions may be symmetricallyformed with respect to a central axis of the micro shutter.

In an example embodiment, the sub-concave portions may be asymmetricallyformed with respect to a central axis of the micro shutter.

In an example embodiment, the sub-concave portions may be formedadjacent to a central axis of the micro shutter.

In an example embodiment, the sub-concave portions may be formed atfirst and second sides of the micro shutter to which the first andsecond driving electrodes are connected.

In an example embodiment, the sub-concave portion may have a cone shapeor a quadrangular pyramid shape.

In an example embodiment, the display substrate further includes acircuit part disposed on the base substrate and providing a drivingsignal to the first and second driving electrodes.

In an example embodiment, the circuit part may include a storagecapacitor including at least one electrode. The electrode may be formedcorresponding to an area where the micro shutter is disposed and besubstantially parallel with the opening.

According to another example embodiment of the present invention, amethod of manufacturing a display substrate includes forming a firstsacrificial layer on a base substrate, and forming an anchor hole and asub-hole having a depth smaller than that of the anchor hole in thefirst sacrificial layer. A second sacrificial layer is formed on thefirst sacrificial layer. In the second sacrificial layer, an electrodehole overlaps with the anchor hole and a main hole overlaps with thesub-hole. A metal layer is formed on the second sacrificial layer. Themetal layer is patterned to form a micro shutter and a first drivingelectrode. The micro shutter includes a flat portion having at least oneopening, a main concave portion adjacent to the opening and extending infrom the flat portion to a first depth, and at least one sub-concaveportion extending in from a bottom surface of the main concave portionto a second depth. The first driving electrode is connected to a firstside of the micro shutter. The first and second sacrificial layers areremoved.

In an example embodiment, forming a first sacrificial layer may furtherinclude forming a plurality of sub-holes having smaller depths than thedepth of the anchor hole. Depths of the sub-holes may be different fromeach other.

In an example embodiment, the metal layer may include an amorphoussilicon layer and an aluminum layer.

In an example embodiment, before forming the first sacrificial layer,the method of manufacturing a display substrate may further includeforming a semiconductor pattern on the base substrate, forming a firstconductive pattern on the base substrate including the semiconductorpattern, and forming a second conductive pattern on the base substrateincluding the first conductive pattern is formed. The first conductivepattern may overlap with the semiconductor pattern. The secondconductive pattern may electrically contact the semiconductor patternand/or the first conductive pattern through a contact hole.

In an example embodiment, the first conductive pattern may include atleast one first electrode of a storage capacitor. The first electrodemay be disposed on the base substrate to correspond to an area where themicro shutter is disposed and may be substantially parallel with theopening. The second conductive pattern may include a second electrode ofthe storage capacitor overlapping the first electrode.

According to another example embodiment of the present invention, adisplay panel includes a first display substrate, a second displaysubstrate and a fluidic layer disposed between the first and seconddisplay substrates. The first display substrate includes a first basesubstrate, a micro shutter including a flat portion having at least oneopening, a main concave portion adjacent to the opening and extending infrom the flat portion to a first depth, and at least one sub-concaveportion extending in from a bottom surface of the main concave portionto a second depth, a first driving electrode connected to a first sideof the micro shutter, a second driving electrode connected to a secondside of the micro shutter, the second side positioned opposite to thefirst side, and a plurality of anchors fixing the first and seconddriving electrodes on the base substrate. The second display substrateincludes a second base substrate facing the first base substrate, and areflecting layer formed on the second base substrate and having at leastone transmitting hole corresponding to an area where the micro shutteris formed.

In an example embodiment, the micro shutter may include a plurality ofsub-concave portions. Depths of the sub-concave portions extending infrom the bottom surface of the main concave portion may be differentfrom each other.

In an example embodiment, the display panel may further include acircuit part disposed on the first base substrate and providing adriving signal to the first and second driving electrodes.

In an example embodiment, the circuit part may include a storagecapacitor including at least one electrode. The electrode may be formedcorresponding to an area where the micro shutter is disposed and besubstantially parallel with the opening.

In an example embodiment, the electrode of the storage capacitor mayoverlap with the reflecting layer.

According to another example embodiment of the present invention, adisplay substrate includes a base substrate and a micro shuttercomprising a flat portion having at least one opening, a plurality ofmain concave portions extending in from the flat portion to a firstdepth, and a plurality of sub-concave portions extending in from abottom surface of the main concave portion to a plurality of seconddepths, wherein the plurality of second depths are different from eachother.

According to the example embodiments, a plurality of sub-concaveportions having depths different from each other are Ruined on the microshutter, so that a static friction between the base substrate and themicro shutter spaced apart and floated from the base substrate may bedecreased.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features of the present invention will become moreapparent by describing in detail example embodiments thereof withreference to the accompanying drawings, in which:

FIG. 1 is a plan view illustrating a portion of a display panelaccording to an example embodiment of the present invention;

FIG. 2 is a cross-sectional view taken along a line I-I′ of FIG. 1;

FIG. 3 is an equivalent circuit diagram illustrating a circuit part ofFIG. 1;

FIGS. 4A to 4C are plan views to explain a method for manufacturing thecircuit part of FIG. 1;

FIGS. 5A to 5C are cross-sectional views to explain a method formanufacturing a shutter part of FIG. 1;

FIGS. 6A to 6D are plan views to explain a distribution of sub-concaveportions according to another example embodiment of the presentinvention;

FIGS. 7A and 7B are conceptual diagrams to explain opening of a shutterpart of FIG. 1; and

FIGS. 8A and 8B are conceptual diagrams to explain a closing of theshutter part of FIG. 1.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

Hereinafter, embodiments of the present invention will be explained indetail with reference to the accompanying drawings.

FIG. 1 is a plan view illustrating a portion of a display panelaccording to an example embodiment of the present invention.

Referring to FIG. 1, the display panel includes a plurality of pixels,and each pixel P includes a circuit part 100 and a shutter part 200.

The circuit part 100 includes a plurality of signal lines DL, GL, CL, RLand UL, a plurality of transistors TR1, TR2, TR3, TR4, TR5 and TR6, anda storage capacitor CST (see FIG. 2). The circuit part 100 iselectrically connected to the shutter part 200 to control the shutterpart 200.

The shutter part 200 includes a micro shutter 210, a plurality ofdriving electrodes 221 and 222, a plurality of reference electrodes 231and 232, and a plurality of anchors A1, A2, . . . , A10.

The micro shutter 210 includes a flat portion 211, at least one opening212 formed on the flat portion 211, and a main-concave portion 213. Theopening 212 extends along a second direction D2 crossing a firstdirection D1 along which the micro shutter 210 moves. The main-concaveportion 213 is formed adjacent to the opening 212, and extends along thesecond direction D2. The main-concave portion 213 has a first depth d1from the flat portion 211. The main-concave portion 213 prevents themicro shutter 210 from being bent. A main-concave portion 213 may beformed at one side of an opening 212, or at two sides of an opening 212.

According to an embodiment, one or more of the main-concave portions 213includes at least one sub-concave portion 215. The sub-concave portion215 is extended to a second depth (e.g., depth d2) from a bottom surfaceof the main-concave portion 213. According to an embodiment, the microshutter 210 includes a plurality of sub-concave portions 215. Depths ofthe sub-concave portions 215 from the bottom surface of the main-concaveportion 213 may be different from each other. According to embodiments,the sub-concave portions 215 have a cone shape or a quadrangular pyramidshape. The sub-concave portion 215 decreases a static friction at themain-concave portion 213.

The driving electrodes includes a first driving electrode 221 connectedto a first side of the micro shutter 210, and a second driving electrode222 connected to a second side of the micro shutter opposite to thefirst side. According to an embodiment, each of the first and seconddriving electrodes 221 and 222 has a symmetrical Y-shape with respect toa central axis CA of the micro shutter 210.

The reference electrodes include a first reference electrode 231 spacedapart from the first driving electrode 221 and a second referenceelectrode 232 spaced apart from the second driving electrode 222.According to an embodiment, each of the first and second referenceelectrodes 231 and 232 has a symmetrical V-shape with respect to thecentral axis CA. The first reference electrode 231 includes a firstextending electrode 231 a which is connected to the first referenceelectrode 231 and substantially parallel with the first referenceelectrode 231. The second reference electrode 232 includes a secondextending electrode 232 a which is connected to the second referenceelectrode 232 and substantially parallel with the second referenceelectrode 232. The first and second extending electrodes 231 a and 232 areinforce the first and second reference electrodes 231 and 232 againstan elastic force.

The anchors A1, A2, . . . , A10 fix the first driving electrode 221, thesecond driving electrode 222, the first reference electrode 231 and thesecond reference electrode 232. Each of the anchors A1, A2, . . . , A10has a height.

The first and second anchors A1 and A2 fix end portions of the firstdriving electrode 221, and apply a driving voltage to the first drivingelectrode 221. The third and fourth anchors A3 and A4 fix end portionsof the second driving electrode 222, and apply a driving voltage to thesecond driving electrode 222.

The fifth anchor A5 fixes the first reference electrode 231, and appliesa reference voltage to the first reference electrode 231. The sixth andseventh anchors A6 and A7 fix end portions of the first extendingelectrode 231 a. A reference voltage is applied to the sixth and seventhanchors A6 and A7. The eighth anchor A8 fixes the second referenceelectrode 232, and applies a reference voltage to the second referenceelectrode 232. The ninth and tenth anchors A9 and A10 fix end portionsof the second extending electrode 232 a. A reference voltage is appliedto the ninth and tenth anchors A9 and A10.

FIG. 2 is a cross-sectional view taken along a line I-I′ of FIG. 1. FIG.3 is an equivalent circuit diagram illustrating a circuit part of FIG.1.

Referring to FIGS. 1 and 2, the display panel includes a first displaysubstrate 300, a second substrate 400 and a fluidic layer 500.

The first display substrate 300 includes a first base substrate 301, thecircuit part 100 formed on the first base substrate 301, and the shutterpart 200 formed on the circuit part 100.

The circuit part 100 includes the plurality of signal lines DL, GL, CL,UL and RL, the plurality of transistors TR1, TR2, TR3, TR4, TR5 and TR6,the storage capacitor CST, a first node N1 and a second node N2.

For example, referring to FIG. 3, a first transistor TR1 is connected toa gate line GL, a data line DL and a second transistor TR2. The secondtransistor TR2 is connected to an up-data line UL, the first transistorTR1 and a third transistor TR3. The third transistor TR3 is connected tothe second transistor TR2, a reference line RL and the first node N1.The fourth transistor TR4 is connected to the second transistor TR2, acontrol line CL, and the first node N1. The fifth transistor TR5 isconnected to the third transistor TR3, the control line CL, and thesecond node N2. The sixth transistor TR6 is connected to the thirdtransistor TR3, the reference line RL, and the second node N2. Accordingto an embodiment, each of the first, second, third and sixth transistorsTR1, TR2, TR3 and TR6 is an N-type transistor, and each of the firth andfifth transistors TR4 and TR5 is a P-type transistor. Alternatively, thedoping of the transistors may be reversed.

Each of the first to sixth transistors TR1, TR2, TR3, TR4, TR5 and TR6includes a semiconductor 111, a gate electrode GE1 formed on thesemiconductor 111, a source electrode SE1 connected to the semiconductor111 and a drain electrode DE1 connected to the semiconductor 111.

The storage capacitor CST includes a first electrode CE1 connected tothe first transistor TR1, and a second electrode CE2 connected to thereference line RL. For example, the storage capacitor CST is disposed tooverlap an area where the micro shutter 210 is formed, and includes aplurality of first electrodes CE1 connected in parallel and a pluralityof second electrodes CE2 overlapping with the first electrodes CE1.

The first node N1 is electrically connected to the first drivingelectrode 221 of the shutter part 200. The second node N2 iselectrically connected to the second electrode 222 of the shutter part200. In addition, the reference line RL is electrically connected to thefirst reference electrode 231 of the shutter part 200 and the secondreference electrode 232 of the shutter part 200.

In addition, with reference to the transistors, the circuit part 100further includes a first insulation layer 120 formed between thesemiconductor 111 and the gate electrodes GE, a second insulation layer130 formed between the gate electrodes GE and the source electrodes SE,and a third insulation layer 140 formed on the source electrodes SE.

The shutter part 200 is disposed on the first base substrate 301 onwhich the circuit part 100 is formed. The shutter part 200 includes theanchors A1, A2, . . . , A10, and the first driving electrode 221connected to the anchors A1 and A2, the second driving electrode 222connected to the anchors A3 and A4, the first reference electrode 231connected to the anchors A5, A6 and A7, and the second referenceelectrode 232 connected to the anchors A8, A9 and A10. The shutter part200 includes the micro shutter 210 connected to the first and seconddriving electrodes 221 and 222.

Each of the anchors A1, A2, . . . , A10 is formed on the first basesubstrate 301 on which the circuit part 100 is formed, and has a heightcorresponding to a first length L1. The first driving electrode 221, thesecond driving electrode 222, the first reference electrode 231 and thesecond reference electrode 232 are connected to the anchors A1, A2, . .. , A10, and spaced apart from the first base substrate 301 on which thecircuit part 100 is formed by a second length L2.

The micro shutter 210 includes the flat portion 211, the opening 212,the main-concave portion 213 and the sub-concave portion 215. The flatportion 211 is spaced apart from the first base substrate 301 on whichthe circuit part 100 is formed by the first length L1. The flat portion211 is partially removed to form the opening 212. For example, theopening 212 partially overlaps with a first area EA where the storagecapacitor CST is formed, and partially overlaps with a second area OAwhere the storage capacitor CST is not formed.

The bottom surface of the main-concave portion 213 is spaced apart fromthe first base substrate 301 on which the circuit part 100 is formed bythe second length L2. A bottom surface of the sub-concave portion 215 isspaced apart from the first base substrate 301 on which the circuit part100 is formed by the third length L3. In addition, the main-concaveportion 213 extends in from the flat portion 211 by a first depth d1.The sub-concave portion 215 extends in from the bottom surface of themain-concave portion 213 by a second depth d2. According to anembodiment, the second depth is smaller than the first depth d1.

The micro shutter 210 includes a plurality of the sub-concave portions215. According to an embodiment, the bottom surface of each of thesub-concave portions 215 is spaced apart from the first base substrate301 on which the circuit part 100 is formed by lengths different fromeach other. The sub-concave portions 215 decrease static frictionbetween the micro shutter 210 and the circuit part 100.

The second display substrate 400 includes a second base substrate 401and a reflecting layer 410 formed on the second base substrate 401.

The reflecting layer 410 has at least one transmitting hole H. Thetransmitting hole(s) H is formed in an area of the second base substrate401 corresponding to an area in which the micro shutter 210 is formed.For example, according to an embodiment, the transmitting hole H isformed on the second base substrate 401 corresponding to the second areaOA where the storage capacitor CST is not formed. The reflecting layer410 reflects light which does not pass through the transmitting hole Hof the second base substrate 401 back toward the first display substrate300 so that the light might be reused for transmission through thetransmitting hole H. Thus, the reflecting layer 410 improves efficiencyby providing light back to the first display substrate 300.

FIGS. 4A to 4C are plan views to explain a method for manufacturing thecircuit part of FIG. 1.

Referring to FIGS. 2 and 4A, a semiconductor pattern is formed on thefirst base substrate. The semiconductor pattern includes a firstsemiconductor 111, a second semiconductor 112, a third semiconductor113, a fourth semiconductor 114, a fifth semiconductor 115, and a sixthsemiconductor 116. A insulation layer 120 is formed on the first basesubstrate 301 including the first to sixth semiconductors 111, 112, 113,114, 115 and 116.

Referring to FIGS. 2 and 4B, a first conductive pattern is formed on thesecond insulation layer 120. The first conductive pattern includes adata line DL, a first capacitor electrode CE1, gate electrodes GE1, GE2,GE3, GE4, GE5 and GE6. A second insulation layer 130 is formed on thefirst base substrate 301 including the first conductive pattern.

Referring to FIGS. 2 and 4C, a plurality of contact holes CT is formedby patterning the first and second insulation layers 120 and 130. Asecond conductive pattern is formed on the first base substrate 301. Thesecond conductive pattern includes a gate line GL, a control line CL, areference line RL, a up-data line UL, source electrodes SE1, SE2, SE3,SE4, SE5 and SE6, and drain electrodes DE1, DE2, DE3, DE4, DE5 and DE6.The second conductive pattern makes contact with the semiconductorpattern or the first conductive pattern through the contact holes CT. Athird insulation layer 140 is formed on the first base substrate 301including the second conductive pattern.

Although not shown in figures, a shielding pattern may be formed on thefirst base substrate 301 including the third insulation layer 140.According to an embodiment, the shielding pattern is formed on the thirdinsulation layer 140 of the first base-substrate corresponding to anarea where the first and second reference electrodes 231 and 232 of theshutter part 200 are formed. The shielding pattern prevents anelectrical signal from being provided to the first and second referenceelectrodes 231 and 232. The electrical signal is applied to the signallines and electrodes of the circuit part 100 formed under the first andsecond reference electrodes 231 and 232.

FIGS. 5A to 5C are cross-sectional views to explain a method formanufacturing a shutter part of FIG. 1.

Referring to FIGS. 2, 4C and 5A, a first sacrificial layer 201 is formedon the first base substrate 301 on which the circuit part 100 is formed.An anchor hole 201 a and sub-holes 201 b and 201 c having second andthird depths d2 and d3 different from each other are formed bypatterning the first sacrificial layer 201. The anchor holes 201 a areformed in areas where the anchors A1, A2, . . . , A10 are formed. Thesub-holes 201 b and 201 c are formed in areas where the sub-concaveportions 215 are formed.

Referring to FIGS. 2, 5A and 5B, a second sacrificial layer 202 isformed on the first base substrate 301 including the first sacrificiallayer 201. Electrode holes 202 a and the main holes 202 b are formed bypatterning the second sacrificial layer 202. The electrode holes 202 aoverlap with the respective anchor holes 201 a, and are formed in areaswhere the driving electrodes 221 and 222 and the reference electrodes231 and 232 are formed. The main holes 202 b overlap with the sub-holes201 b and 201 c, and are formed in areas where the main-concave portions213 are formed. Each of the electrode holes 202 a and the main holes 202b has a first depth d1. According to an embodiment, the first depth d1is lager than the second depth d2.

Referring to FIGS. 2, 5B and 5C, a metal layer 203 is formed on thefirst base substrate 301 including the second sacrificial layer 202. Themetal layer 203 includes, for example, an amorphous silicon layer and analuminum layer.

The metal layer 203 fills in and/or lines the anchor hole 201 a, thesub-holes 201 b and 201 c, the electrode holes 202 a, and the main holes202 b formed on the first and second sacrificial layers 201 and 202, toform the anchors A1, A2, . . . , A10, the driving electrodes 221 and222, the reference electrodes 231 and 232, the main concave portions 213and the sub-concave portions 215. In addition, the metal layer 203 isformed on a flat surface of the second sacrificial layer 202, so that aflat portion 211 of the micro shutter is formed.

A photo mask pattern 204 is formed on the first base substrate 301including portions of the metal layer 203. The photo mask pattern 204 isformed in the shutter part 200, and formed on the second sacrificiallayer 202. The photo mask pattern 204 includes a hole pattern 204 aformed areas corresponding to the openings 212 of the micro shutter 210.The metal layer 203 is patterned using the photo mask pattern 204. Thus,the metal layer 203 is patterned into the shutter part 200 having theopenings 212.

Then, the first sacrificial layer 201, the second sacrificial layer 202and the photo mask pattern 204 are removed. The micro shutter 210, thedriving electrodes 221 and 222 connected to the micro shutter 210, andthe reference electrodes 231 and 232 facing the driving electrodes 221and 222 are formed on the circuit part 100. The shutter part 200,including the micro shutter 210, is fixed by the anchors A1, A2, . . . ,A10, so that the shutter part 200, including the micro shutter 210, isspaced apart and floated from the first base substrate 301. Thus, theshutter part 200 is formed on the first base substrate 301 on which thecircuit part 100 is formed.

Then, according to an embodiment, an insulation layer (not shown) isformed on the first base substrate 301 on which the shutter part 200 isformed.

FIGS. 6A to 6D are plan views to explain a distribution of sub-concaveportions according to another example embodiment of the presentinvention.

Referring to FIG. 6A, a micro shutter 610 includes a plurality ofsub-concave portion 615. The sub-concave portions 615 are asymmetricallydisposed with respect to a central axis CA of the micro shutter 610.Depths of the sub-concave portions 615 are different from each other.Each of the sub-concave portions 615 has, for example, a cone shape or aquadrangular pyramid shape.

Referring to FIG. 6B, a micro shutter 710 includes a plurality ofsub-concave portions 715. The sub-concave portions 715 are symmetricallydisposed with respect to a central axis CA of the micro shutter 710.Depths of the sub-concave portions 715 are different from each other.Each of the sub-concave portions 715 has, for example, a cone shape or aquadrangular pyramid shape.

Referring to FIG. 6C, a micro shutter 810 includes a plurality ofsub-concave portions 815. The sub-concave portions 815 are disposedadjacent to a central axis CA of the micro shutter 810. Depths of thesub-concave portions 815 are different from each other. Each of thesub-concave portions 815 has, for example, a cone shape or aquadrangular pyramid shape.

Referring to FIG. 6D, a micro shutter 910 includes a plurality ofsub-concave portions 915. The sub-concave portions 915 are disposed atboth sides of the micro shutter 910. Depths of the sub-concave portions915 are different from each other. Each of the sub-concave portions 915has, for example, a cone shape or a quadrangular pyramid shape.

FIGS. 7A and 7B are conceptual diagrams to explain opening of a shutterpart of FIG. 1.

Referring to FIGS. 7A and 7B, in a first period, a first data signalhaving a relatively high level is applied to the data line DL, and agate signal having the relatively high level is applied to the gate lineGL. In addition, a control signal having the relatively high level isapplied to the control line CL, and an up-data signal having arelatively low level is applied to the up-data line UL. In addition, areference signal having the relatively low level is applied to thereference line RL.

As a result, the first transistor TR1 is turned on, the first datasignal is charged at the storage capacitor CST. The second transistorTR2 is turned off. As the second transistor TR2 is turned off, a signalhaving the relatively low level is applied to the third transistor TR3and the fourth transistor TR4. As a result, the third transistor TR3 isturned off, and the fourth transistor TR4 is turned on. As the fourthtransistor TR4 is turned on, the control signal having the relativelyhigh level is applied to the first node N1, the fifth transistor TR5 andthe sixth transistor TR6. The fifth transistor TR5 is turned off, andthe sixth transistor TR6 is turned on. As the sixth transistor TR6 isturned on, the reference signal applied to the reference line RL andhaving the relatively low level is applied to the second node N2. Asignal having the relatively high level is applied at the first node N1.A signal having the relatively low level is applied at the second nodeN2.

The first node N1 is electrically connected to a first driving electrode221 of the micro shutter 210. The second node N2 is electricallyconnected to a second driving electrode 222 of the micro shutter 210.Alternatively, the reference voltage having the relatively low level isapplied to the first and second reference electrodes 231 and 232. Due toan electrostatic force, the first driving electrode 221 and the firstreference electrode 231 pull each other. The second driving electrode222 and the second reference electrode 232 push each other. The microshutter 210 is moved toward the first reference electrode 231, so thatthe opening 212 overlaps with the transmitting hole H of the seconddisplay substrate 400.

As a result, the light passes through the micro shutter 210, and a pixeldefined by the micro shutter 210 displays an image having a relativelyhigh gray scale.

FIGS. 8A and 8B are conceptual diagrams to explain a closing of theshutter part of FIG. 1.

Referring to FIGS. 8A and 8B, in a second period, a second data signalhaving the relatively low level is applied to the data line, and a gatesignal having the relatively high level is applied to the gate line GL.In addition, a control signal having the relatively high level isapplied to the control line CL, and an up-data signal having arelatively high level is applied to the up-data line UL. In addition, areference signal having the relatively low level is applied to thereference line RL.

As a result, the first transistor TR1 is turned on, and the second datasignal is charged at the storage capacitor CST. The second transistorTR2 is turned on. As the second transistor TR2 is turned on, the thirdtransistor TR3 is turned on and the fourth transistor TR4 is turned off.As the fourth transistor TR4 is turned off, a signal having therelatively low level is applied to the first node N1, the fifthtransistor TR5 and the sixth transistor TR6. The fifth transistor TR5 isturned on, and the sixth transistor TR6 is turned off. As the fifthtransistor TR5 is turned on, the control signal, which is applied to thecontrol line CL and having the relatively high level, is applied to thesecond node N2. A signal having a relatively low level is applied to thefirst node N1, and a signal having relatively high level is applied tothe second node N2.

Due to the electrostatic force, the first driving electrode 221 and thefirst reference electrode 231 push each other. The second drivingelectrode 222 and the second reference electrode 232 pull each other.The micro shutter 210 moves toward the second reference electrode 232,so that the opening 212 overlaps with the reflecting layer 410 of thesecond display substrate 400.

As a result, the light is blocked by the micro shutter 210, and a pixeldefined by the micro shutter 210 displays an image having a relativelylow gray scale.

According to example embodiments of the present invention, a pluralityof sub-concave portions have a depth different each other on the microshutter 210, so that a static friction between the base substrate andthe micro shutter 210 spaced apart and floated from the base substratemay be decreased.

The foregoing is illustrative of embodiments of the present inventionand is not to be construed as limiting thereof. Although a few exampleembodiments of the present invention have been described, those skilledin the art will readily appreciate that many modifications are possiblein the example embodiments without materially departing from the novelteachings and advantages of the present invention. Accordingly, all suchmodifications are intended to be included within the scope of theembodiments of the present invention as defined in the claims.

What is claimed is:
 1. A display substrate comprising: a base substrate;a micro shutter comprising a flat portion having at least one opening, amain concave portion adjacent to the opening and extending in from theflat portion to a first depth, and at least one sub-concave portionextending in from a bottom surface of the main concave portion to asecond depth; a first driving electrode connected to a first side of themicro shutter; a second driving electrode connected to a second side ofthe micro shutter, the second side positioned opposite to the firstside; and a plurality of anchors fixing the first and second drivingelectrodes on the base substrate.
 2. The display substrate of claim 1,further comprising a first reference electrode spaced apart from thefirst driving electrode, and fixed on the base substrate by at least oneof the anchors; and a second reference electrode spaced apart from thesecond driving electrode, and fixed on the base substrate by at leastone of the anchors.
 3. The display substrate of claim 1, wherein themicro shutter comprises a plurality of sub-concave portions, and depthsof the sub-concave portions from the bottom surface of the main concaveportion are different from each other.
 4. The display substrate of claim3, wherein the sub-concave portions are symmetrically formed withrespect to a central axis of the micro shutter.
 5. The display substrateof claim 3, wherein the sub-concave portions are asymmetrically formedwith respect to a central axis of the micro shutter.
 6. The displaysubstrate of claim 3, wherein the sub-concave portions are formedadjacent to a central axis of the micro shutter.
 7. The displaysubstrate of claim 3, wherein the sub-concave portions are formed at thefirst and second sides of the micro shutter.
 8. The display substrate ofclaim 1, wherein the sub-concave portion has a cone shape or aquadrangular pyramid shape.
 9. The display substrate of claim 1, furthercomprising a circuit part disposed on the base substrate, and providinga driving signal to the first and second driving electrodes.
 10. Thedisplay substrate of claim 9, wherein the circuit part comprises astorage capacitor comprising at least one electrode, and the electrodeis formed corresponding to an area where the micro shutter is disposedand is substantially parallel with the opening.
 11. A display panelcomprising: a first display substrate comprising: a first basesubstrate; a micro shutter comprising a flat portion having at least oneopening, a main concave portion adjacent to the opening and extending infrom the flat portion to a first depth, and at least one sub-concaveportion extending in from a bottom surface of the main concave portionto a second depth; a first driving electrode connected to a first sideof the micro shutter; a second driving electrode connected to a secondside of the micro shutter, the second side positioned opposite to thefirst side; and a plurality of anchors fixing the first and seconddriving electrodes on the base substrate; a second display substratecomprising a second base substrate facing the first base substrate, anda reflecting layer formed on the second base substrate and having atleast one transmitting hole corresponding to an area where the microshutter is formed; and a fluidic layer disposed between the first andsecond display substrates.
 12. The display panel of claim 11, whereinthe micro shutter comprises a plurality of sub-concave portions, anddepths of the sub-concave portions extending in from the bottom surfaceof the main concave portion are different from each other.
 13. Thedisplay panel of claim 11, further comprising a circuit part disposed onthe first base substrate, and providing a driving signal to the firstand second driving electrodes.
 14. The display panel of claim 13,wherein the circuit part comprises a storage capacitor comprising atleast one electrode, and the electrode is formed corresponding to anarea where the micro shutter is disposed and is substantially parallelwith the opening.
 15. The display panel of claim 14, wherein theelectrode of the storage capacitor overlaps with the reflecting layer.